New attribute to turn font fallback on or off. (#105553)

2003-02-29  Noah Levitt  <nlevitt@columbia.edu>

	* docs/pango_markup.sgml:
	* docs/tmpl/text-attributes.sgml:
	* pango/pango-attributes.c:
	* pango/pango-attributes.h:
	* pango/pango-context.c:
	* pango/pango-markup.c: New attribute to turn font fallback on or off.
	(#105553)

11 files changed, 170 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index 1d5b533a..54b51c5b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2003-02-29  Noah Levitt  <nlevitt@columbia.edu>
+
+	* docs/pango_markup.sgml:
+	* docs/tmpl/text-attributes.sgml:
+	* pango/pango-attributes.c:
+	* pango/pango-attributes.h:
+	* pango/pango-context.c:
+	* pango/pango-markup.c: New attribute to turn font fallback on or off.
+	(#105553)
+
 Sun Feb 29 10:54:55 2004  Owen Taylor  <otaylor@redhat.com>
 
 	* modules/arabic/arabic-ot.c (arabic): Add joining
diff --git a/ChangeLog.pre-1-10 b/ChangeLog.pre-1-10
index 1d5b533a..54b51c5b 100644
--- a/ChangeLog.pre-1-10
+++ b/ChangeLog.pre-1-10
@@ -1,3 +1,13 @@
+2003-02-29  Noah Levitt  <nlevitt@columbia.edu>
+
+	* docs/pango_markup.sgml:
+	* docs/tmpl/text-attributes.sgml:
+	* pango/pango-attributes.c:
+	* pango/pango-attributes.h:
+	* pango/pango-context.c:
+	* pango/pango-markup.c: New attribute to turn font fallback on or off.
+	(#105553)
+
 Sun Feb 29 10:54:55 2004  Owen Taylor  <otaylor@redhat.com>
 
 	* modules/arabic/arabic-ot.c (arabic): Add joining
diff --git a/ChangeLog.pre-1-4 b/ChangeLog.pre-1-4
index 1d5b533a..54b51c5b 100644
--- a/ChangeLog.pre-1-4
+++ b/ChangeLog.pre-1-4
@@ -1,3 +1,13 @@
+2003-02-29  Noah Levitt  <nlevitt@columbia.edu>
+
+	* docs/pango_markup.sgml:
+	* docs/tmpl/text-attributes.sgml:
+	* pango/pango-attributes.c:
+	* pango/pango-attributes.h:
+	* pango/pango-context.c:
+	* pango/pango-markup.c: New attribute to turn font fallback on or off.
+	(#105553)
+
 Sun Feb 29 10:54:55 2004  Owen Taylor  <otaylor@redhat.com>
 
 	* modules/arabic/arabic-ot.c (arabic): Add joining
diff --git a/ChangeLog.pre-1-6 b/ChangeLog.pre-1-6
index 1d5b533a..54b51c5b 100644
--- a/ChangeLog.pre-1-6
+++ b/ChangeLog.pre-1-6
@@ -1,3 +1,13 @@
+2003-02-29  Noah Levitt  <nlevitt@columbia.edu>
+
+	* docs/pango_markup.sgml:
+	* docs/tmpl/text-attributes.sgml:
+	* pango/pango-attributes.c:
+	* pango/pango-attributes.h:
+	* pango/pango-context.c:
+	* pango/pango-markup.c: New attribute to turn font fallback on or off.
+	(#105553)
+
 Sun Feb 29 10:54:55 2004  Owen Taylor  <otaylor@redhat.com>
 
 	* modules/arabic/arabic-ot.c (arabic): Add joining
diff --git a/ChangeLog.pre-1-8 b/ChangeLog.pre-1-8
index 1d5b533a..54b51c5b 100644
--- a/ChangeLog.pre-1-8
+++ b/ChangeLog.pre-1-8
@@ -1,3 +1,13 @@
+2003-02-29  Noah Levitt  <nlevitt@columbia.edu>
+
+	* docs/pango_markup.sgml:
+	* docs/tmpl/text-attributes.sgml:
+	* pango/pango-attributes.c:
+	* pango/pango-attributes.h:
+	* pango/pango-context.c:
+	* pango/pango-markup.c: New attribute to turn font fallback on or off.
+	(#105553)
+
 Sun Feb 29 10:54:55 2004  Owen Taylor  <otaylor@redhat.com>
 
 	* modules/arabic/arabic-ot.c (arabic): Add joining
diff --git a/docs/pango_markup.sgml b/docs/pango_markup.sgml
index e988e1d2..56f2ddae 100644
--- a/docs/pango_markup.sgml
+++ b/docs/pango_markup.sgml
@@ -135,6 +135,16 @@ subscript, positive for superscript.
 </para></listitem>
 </varlistentry>
 
+<varlistentry><term>fallback</term>
+<listitem><para>
+'true' or 'false' whether to enable fallback. If disabled, then characters
+will only be used from the closest matching font on the system. No fallback
+will be done to other fonts on the system that might contain the characters
+in the text.  Fallback is enabled by default. Most applications should not
+disable fallback.
+</para></listitem>
+</varlistentry>
+
 <varlistentry><term>lang</term>
 <listitem><para>
 A language code, indicating the text language
diff --git a/docs/tmpl/text-attributes.sgml b/docs/tmpl/text-attributes.sgml
index ce2c5f64..4707232f 100644
--- a/docs/tmpl/text-attributes.sgml
+++ b/docs/tmpl/text-attributes.sgml
@@ -43,6 +43,7 @@ attribute is listed in parentheses after the description.
 @PANGO_ATTR_RISE: baseline displacement (#PangoAttrInt)
 @PANGO_ATTR_SHAPE: shape (#PangoAttrShape)
 @PANGO_ATTR_SCALE: font size scale factor (#PangoAttrScale)
+@PANGO_ATTR_FALLBACK: whether fallback is enabled (#PangoAttrInt)
 
 <!-- ##### MACRO PANGO_TYPE_ATTR_TYPE ##### -->
 <para>
diff --git a/pango/pango-attributes.c b/pango/pango-attributes.c
index e2441ac9..57017cb8 100644
--- a/pango/pango-attributes.c
+++ b/pango/pango-attributes.c
@@ -643,6 +643,33 @@ pango_attr_scale_new (double scale_factor)
   return pango_attr_float_new (&klass, scale_factor);
 }
 
+/**
+ * pango_attr_fallback_new:
+ * @enable_fallback: %TRUE if we should fall back on other fonts 
+ *                   for characters the active font is missing.
+ * 
+ * Create a new font fallback attribute.
+ *
+ * If fallback is disabled, characters will only be used from the
+ * closest matching font on the system. No fallback will be done to
+ * other fonts on the system that might contain the characters in the
+ * text.
+ * 
+ * Return value: the new #PangoAttribute.
+ **/
+PangoAttribute *
+pango_attr_fallback_new (gboolean enable_fallback)
+{
+  static const PangoAttrClass klass = {
+    PANGO_ATTR_FALLBACK,
+    pango_attr_int_copy,
+    pango_attr_int_destroy,
+    pango_attr_int_equal,
+  };
+
+  return pango_attr_int_new (&klass, (int)enable_fallback);
+}
+
 static PangoAttribute *
 pango_attr_shape_copy (const PangoAttribute *attr)
 {
diff --git a/pango/pango-attributes.h b/pango/pango-attributes.h
index 5a29f706..30a2fb24 100644
--- a/pango/pango-attributes.h
+++ b/pango/pango-attributes.h
@@ -80,7 +80,8 @@ typedef enum
   PANGO_ATTR_STRIKETHROUGH,	/* PangoAttrInt */
   PANGO_ATTR_RISE,		/* PangoAttrInt */
   PANGO_ATTR_SHAPE,		/* PangoAttrShape */
-  PANGO_ATTR_SCALE              /* PangoAttrFloat */
+  PANGO_ATTR_SCALE,             /* PangoAttrFloat */
+  PANGO_ATTR_FALLBACK,          /* PangoAttrInt */
 } PangoAttrType;
 
 typedef enum {
@@ -179,6 +180,7 @@ PangoAttribute *pango_attr_rise_new          (int                         rise);
 PangoAttribute *pango_attr_shape_new         (const PangoRectangle       *ink_rect,
 					      const PangoRectangle       *logical_rect);
 PangoAttribute *pango_attr_scale_new         (double                      scale_factor);
+PangoAttribute *pango_attr_fallback_new      (gboolean                    enable_fallback);
 
 GType              pango_attr_list_get_type      (void) G_GNUC_CONST;
 PangoAttrList *    pango_attr_list_new           (void);
diff --git a/pango/pango-context.c b/pango/pango-context.c
index 520ddff1..e0c67879 100644
--- a/pango/pango-context.c
+++ b/pango/pango-context.c
@@ -515,6 +515,8 @@ struct _ItemizeState
   
   PangoFontset *current_fonts;
   ShaperFontCache *cache;
+  PangoFont *base_font;
+  gboolean enable_fallback;
   
   GSList *exact_engines;
   GSList *fallback_engines;
@@ -534,10 +536,24 @@ update_embedding_end (ItemizeState *state)
   state->changed |= EMBEDDING_CHANGED;
 }
 
+static PangoAttribute *
+find_attribute (GSList        *attr_list,
+                PangoAttrType  type)
+{
+  GSList *node;
+  
+  for (node = attr_list; node; node = node->next)
+    if (((PangoAttribute *) node->data)->klass->type == type)
+      return (PangoAttribute *) node->data;
+
+  return NULL;
+}
+
 static void
 update_attr_iterator (ItemizeState *state)
 {
   PangoLanguage *old_lang;
+  PangoAttribute *fallback;
   int end_index;
   
   pango_attr_iterator_range (state->attr_iter, NULL, &end_index);
@@ -554,6 +570,9 @@ update_attr_iterator (ItemizeState *state)
 				&state->lang, &state->extra_attrs);
   state->copy_extra_attrs = FALSE;
 
+  fallback = find_attribute (state->extra_attrs, PANGO_ATTR_FALLBACK);
+  state->enable_fallback = (fallback == NULL || ((PangoAttrInt *)fallback)->value);
+
   state->changed |= FONT_CHANGED;
   if (state->lang != old_lang)
     state->changed |= LANG_CHANGED;
@@ -639,6 +658,7 @@ itemize_state_init (ItemizeState      *state,
   state->cache = NULL;
   state->exact_engines = NULL;
   state->fallback_engines = NULL;
+  state->base_font = NULL;
   
   state->changed = EMBEDDING_CHANGED | SCRIPT_CHANGED | LANG_CHANGED | FONT_CHANGED;
 }
@@ -813,6 +833,16 @@ get_shaper_and_font_foreach (PangoFontset *fontset,
   return FALSE;
 }
 
+static PangoFont *
+get_base_font (ItemizeState *state)
+{
+  if (!state->base_font)
+    state->base_font = pango_font_map_load_font (state->context->font_map,
+                                                 state->context,
+                                                 state->font_desc);
+  return state->base_font;
+}
+
 static gboolean
 get_shaper_and_font (ItemizeState      *state,
 		     gunichar           wc,
@@ -821,7 +851,9 @@ get_shaper_and_font (ItemizeState      *state,
 {
   GetShaperFontInfo info;
 
-  if (shaper_font_cache_get (state->cache, wc, shape_engine, font))
+  /* We'd need a separate cache when fallback is disabled, but since lookup
+   * with fallback disabled is faster anyways, we just skip caching */
+  if (state->enable_fallback && shaper_font_cache_get (state->cache, wc, shape_engine, font))
     return *shape_engine != NULL;
 
   if (!state->exact_engines && !state->fallback_engines)
@@ -834,24 +866,35 @@ get_shaper_and_font (ItemizeState      *state,
   info.font = NULL;
 
   info.engines = state->exact_engines;
-  pango_fontset_foreach (state->current_fonts, get_shaper_and_font_foreach, &info);
+  if (state->enable_fallback)
+    pango_fontset_foreach (state->current_fonts, get_shaper_and_font_foreach, &info);
+  else 
+    get_shaper_and_font_foreach (NULL, get_base_font (state), &info);
+
   if (info.shape_engine)
     {
       *shape_engine = info.shape_engine;
       *font = info.font;
 
-      shaper_font_cache_insert (state->cache, wc, *shape_engine, *font);
+      /* skip caching if fallback disabled (see above) */
+      if (state->enable_fallback)
+        shaper_font_cache_insert (state->cache, wc, *shape_engine, *font);
 
       return TRUE;
     }
 
   info.engines = state->fallback_engines;
-  pango_fontset_foreach (state->current_fonts, get_shaper_and_font_foreach, &info);
+  if (state->enable_fallback)
+    pango_fontset_foreach (state->current_fonts, get_shaper_and_font_foreach, &info);
+  else 
+    get_shaper_and_font_foreach (NULL, get_base_font (state), &info);
 
   *shape_engine = info.shape_engine;
   *font = info.font;
 
-  shaper_font_cache_insert (state->cache, wc, *shape_engine, *font);
+  /* skip caching if fallback disabled (see above) */
+  if (state->enable_fallback)
+    shaper_font_cache_insert (state->cache, wc, *shape_engine, *font);
       
   return *shape_engine != NULL;
 }
@@ -945,6 +988,12 @@ itemize_state_update_for_new_run (ItemizeState *state)
 							  state->derived_lang);
       state->cache = get_shaper_font_cache (state->current_fonts);
     }
+
+  if ((state->changed & FONT_CHANGED) && state->base_font)
+    {
+      g_object_unref (state->base_font);
+      state->base_font = NULL;
+    }
 }
 
 static void
diff --git a/pango/pango-markup.c b/pango/pango-markup.c
index a0697380..3764fdcb 100644
--- a/pango/pango-markup.c
+++ b/pango/pango-markup.c
@@ -858,6 +858,7 @@ span_parse_func     (MarkupData            *md,
   const char *strikethrough = NULL;
   const char *rise = NULL;
   const char *lang = NULL;
+  const char *fallback = NULL;
   
   g_markup_parse_context_get_position (context,
                                        &line_number, &char_number);
@@ -932,6 +933,11 @@ span_parse_func     (MarkupData            *md,
           CHECK_DUPLICATE (lang);
           lang = values[i];
         }
+      else if (strcmp (names[i], "fallback") == 0)
+        {
+          CHECK_DUPLICATE (fallback);
+          fallback = values[i];
+        }
       else
         {
           g_set_error (error, G_MARKUP_ERROR,
@@ -1182,6 +1188,25 @@ span_parse_func     (MarkupData            *md,
         }
     }
 
+  if (fallback)
+    {
+      if (strcmp (fallback, "true") == 0)
+        add_attribute (tag, pango_attr_fallback_new (TRUE));
+      else if (strcmp (fallback, "false") == 0)
+        add_attribute (tag, pango_attr_fallback_new (FALSE));
+      else
+        {
+          g_set_error (error,
+                       G_MARKUP_ERROR,
+                       G_MARKUP_ERROR_INVALID_CONTENT,
+                       _("'fallback' attribute on <span> tag "
+                         "line %d should have one of the values "
+                         "'true' or 'false': '%s' is not valid"),
+                       line_number, fallback);
+          goto error;
+        }
+    }
+
   if (rise)
     {
       char *end = NULL;